As is the case for all gear shifting there is a desire to minimize the time required to carry out the gear shift. This is because during gear shift there cannot be any torque on the drive line. Gear shifting is also described in the international patent application having the international publication number WO 03/018974. Furthermore in the U.S. Pat. No. 6,089,018 a method of controlling a VTG during gear shift is described.
An engine used in trucks and other heavy motor vehicles, such as buses, is an engine provided with a Variable Turbine Geometry (VTG), also termed Variable Geometry Turbocharger (VGT). One reason for employing VTG technology is that it facilitates fulfillment of emission requirements for i.a. diesel engines.
Moreover, it is desired to maintain a stable exhaust gas pressure when shifting gears. A stable exhaust gas pressure is important for enabling a correct determination of the engine speed generated by the engine. A correctly determined engine speed is a prerequisite for enabling a smooth gear shift.
Hence, there exists a need for a method and a system that is capable of providing a quick gear shin, which at the same time provides for a stable exhaust gas pressure at times when the gear shift is performed so that the gear shift can be executed as quick and as smooth as possible.